How to update properties (rewriteRuleSets) via bicep for existing resource (app gateway)

I want to update rewriteRuleSets for existing app gate way. How to update an existing resource via bicep

I'm a beginer in this field so If possible, please give me an example

resource appGateWay 'Microsoft.Network/applicationGateways@2024-01-01' existing = {
  name: 'existing-agw'
  scope: resourceGroup('preac_RG')
}

resource updatedAppGateWay 'Microsoft.Network/applicationGateways@2024-01-01' = {
  name: 'existing-agw'
  location: 'West Europe'
  properties: {
    rewriteRuleSets: [
      {
        // id: ''
        name: 'cors-test'
        properties: {
          rewriteRules: [
            {
              actionSet: {
                requestHeaderConfigurations: [
                  {
                    headerName: 'Access-Control-Request-Headers'
                    headerValue: '*'
                  }
                ]
                responseHeaderConfigurations: [
                  {
                    headerName: 'Access-Control-Allow-Origin'
                    headerValue: '*'
                  }
                ]
              }
              conditions: [{

              }]
              name: 'test'
              ruleSequence: 5
            }            
          ]
        }
      }
    ]   
  }

}